FIGS. 19A, 19B and 20 show a conventional transmission guide 800 for use in a transmission of an automobile engine. The guide comprises a shoe 810 on which a transmission chain slides, and a separately molded base 820 for supporting, and maintaining the configuration of, the shoe 810. The shoe 810 is formed with hooks 813, which can be provided on both sides of the shoe 810, and the base 820 is cut away to form hook-receiving notches 823. The shoe 810 and the base 820 are assembled twisting the shoe, and engaging the hooks 813 with the notches 813 as described in laid-open Japanese Patent Application No. 2005-114126.
In another known chain guide, disclosed in laid-open Japanese Patent Application No. 2004-150615, the back surface of a synthetic resin shoe is fused to the front surface of a base composed of another synthetic resin.
In the operation of the transmission guide 800 in FIGS. 19A-20, vibration due to load variations cause the shoe 810 to move longitudinally through a distance corresponding to the margin allowed for assembly, as indicated by an arrow in FIG. 19B. Therefore, the hook 813 of the shoe 810 locally abuts an end of the notch 823 of the base 820, causing an excessive concentration of stress in the hook 813. The excessive stress can result in breakage of the hook, separation of the shoe from the base, and failure of the guide to maintain proper travel of the transmission chain.
On the other hand, in the case of a chain guide in which the back of a synthetic resin shoe is fused to the base, it is difficult to maintain the bond between the shoe and the base over a long time, and a shearing force in the direction of the width of the base can cause the shoe to separate from the base.
There is a need for a transmission guide that does not require the engagement of hooks and notches so that it can be more easily assembled, and that is also less subject to failure as a result of breakage of a bond between a synthetic resin shoe and a synthetic resin base, so that trouble-free operation of the guide can be assured over a long time.